There is an ever increasing demand for power conversion and regulation circuitry to operate with increased efficiency and reduced power to accommodate the continuous reduction in size of electronic portable devices. Many times these devices are battery powered, and it is desirable to utilize as little power as possible to operate these devices so that the battery life is extended. Switching regulators have been implemented as an efficient mechanism for providing a regulated output in power supplies. One such type of regulator is known as a switching regulator or switching power supply, which controls the flow of power to a load by controlling the on and off duty-cycle of one or more switches coupled to the load. Many different classes of switching regulators exist today.
A typical power regulator can operate in one of two modes, which can typically depend on the size of the load of the power regulator. One mode is known as a continuous conduction mode (CCM) of operation. In the CCM, the power regulator rapidly switches between the on-state and the off-state (i.e., has a high-frequency duty-cycle), such that the current through the inductor is never fully discharged (i.e., equal to zero). Another mode is known as a discontinuous conduction mode (DCM) of operation. In the DCM, the current flow through the inductor can be substantially completely discharged at each cycle of the power regulator.
A power regulator can be configured to switch between the CCM and the DCM, such as in response to load variations. For example, when the load of a power regulator decreases, the power regulator can switch to the DCM to maintain power efficiency. However, in a synchronized fixed-frequency power regulator, the switching frequency of the power regulator can be approximately the same in both the DCM and the CCM. As a result, upon switching to the CCM, the power regulator can experience substantial switching losses.